Computer systems have evolved to make computers and components smaller, faster, and more powerful, creating new engineering concerns including forming many robust electrical connections in very small spaces, enabling near-zero tolerance flatness of component casings, selecting materials to minimize differences in the coefficients of thermal expansion between the different types of conductive and non-conductive materials used in electronic components. In many data processing systems such as computer systems, programmable electronic systems, telecommunication switching systems, control systems, and the like, electrical components including processors, integrated circuits, memory chips, and application specific integrated circuits (ASICs) are assembled on substrates such as printed circuit boards, other flexible substrates, multi-chip modules, and others. Computer designers have increased power, size and quantity of chips attached to printed circuit boards (PCBs), creating a challenge in cooling the components and systems as well making difficult handling of assembled components due to dense arrangement.
One type of electronic component is a field-replaceable-unit (FRU), an assembly, part, or circuit board that facilitates quick and simple removal from a system and replacement, for example by a user, without transporting the system or product to a repair facility. Examples of FRUs include processor or central processing unit (CPU) modules, memory modules, heat sink assemblies, fans, storage devices, and many others. Operation of FRUs and other components often depends on adequate electrical contact among components and other elements which, in turn, is enabled by compressive force on the assembly.
Various techniques have been employed to supply compressive force on the component assembly, such as clamping with combinations of compressive screws, helical springs, and/or loading plates
Shoulder screws and springs have typically been used to apply force to a heat sink, which can unevenly load the heat sink as the springs are torqued down. Often attachment hardware includes many pieces to attain some degree of even force distribution and employs tools to install or service a component under the heat sink. Furthermore, screws can generate metal debris that can short-circuit system components. Usage of threaded fasteners can involve substantial time for assembly and negatively influences customer satisfaction.